A network-supported approach to layered multicast

Layered multicasting with a layered source coding scheme enables efficient distribution of real-time streaming media over heterogeneous networks such as the Internet. In layered multicast, rate control is required to cope with congestion quickly because packet losses in a layer with higher priority lead greater degradation of the received quality. In addition, rate control for layered multicast is required to assure fair bandwidth allocation among competitive layered multicast sessions at a congested link independent of their start time. We present a novel rate control scheme for layered multicast, called network-supported layered multicast (NLM). In NLM, routers distributed within the network support rate control. NLM avoids packet losses on a layer with high priority and achieves fair bandwidth allocation by filtering and signaling. A router filters a layer with low priority when it detects congestion, or when it is informed that the layer is needless by signaling. Simulation results show NLM offers significant advantages compared with receiver-driven rate control